1. Field of the Invention
The invention relates to a ski boot in which the upper portion of the boot surrounding the lower leg of the skier is adapted to flex relative to the vamp portion of the upper surrounding the foot.
2. Description of Pertinent Materials and Background
The present invention relates to ski boots of the rearentry type, particularly those used in alpine skiing. Such boots are well-known and comprise a rigid shell base mounted on a sole. An upper is provided which is pivotably journalled on the shell base around a generally horizontal axis and comprises a cuff and a rear spoiler. During leg movements the cuff is movable within certain limits around the journal axis, and with a resistance which is proportional to the amplitude of the pivot angle. Flexion of the upper also serves as a shock absorber to absorb sudden forces in the form of brutal and sudden shocks, directed frontwardly or rearwardly relative to the upright position of the skier, as well as adding to the comfort and safety of the skier. This ability of the upper to flex should not, therefore, be arbitrary and unconditional, but rather must be provided in a manner which satisfies certain constraints, as well as varying conditions. Therefore, apparatus have been contemplated which permit modification or adjustment of the degree of flexion. The present invention relates to one such device.
Apparatus known in the prior art, such as those described in French Pat. No. 2,100,490 or French Patent Application No. 2,416,661, comprise a shock absorption apparatus having a single or double action spring which is anchored and extends between a central position situated at an upper position on the front of the cuff and a central point situated towards the front of the foot on the rigid shell base or integral therewith. Besidse the unattractive appearance of such apparatus, such apparatus are very cumbersome and are exposed to being hit in the course of use. Such apparatus can likewise get caught and snag undesirably in the course of use and movement by the skier. There is thus a certain danger in using boots having such systems, and their reliability is reduced because of their random and unpredictable behavior.
In French Pat. No. 2,278,280 an apparatus is proposed which can partially and inherently function to provide results of the type discussed above. However, the apparatus involves removable linkage elements positioned between the rigid shell base and the cuff itself. In the environment of the boot of the present invention which is of the rear-entry type, the apparatus would be secured to rear spoiler rather than the cuff, given the fact that the boot disclosed in the patent is of the front-entry type. In fact, were such an apparatus placed behind the boot, it would serve only as a substitute for a transverse pivot axis, by virtue of its elasticity, of the cuff on the rigid shell base. The solution proposed is thus clearly distinguishable from the present technology.
The two preceding apparatus function only in, or approximately in, a longitudinal vertical plane without involving the important zone which is formed by the flexion fold and the instep. This disadvantage disappears in the solution proposed in French Application Nos. 2,480,575 and 2,484,800.
In the first Application, a flexion band is provided at the lower front portion of the cuff and rests on the rigid shell base. This band is an integral portion of the cuff, or is separate therefrom, and is attached along a transverse journal axis (or immediately adjacent thereto), or fixed at two joints to the rigid shell base. The transmission of force occurs by means of a stop whose position is adjustable. This appealing construction remains relatively complex and breaks the line of the boot, thus detracting from its appearance.
The embodiment proposed in Application 2,484,800 is related to the embodiment disclosed in the preceding Application. This approach is simpler, but adjustment of rigidity is not possible and the apparatus suffers about the same disadvantages. In both cases, the band is attached at its ends and works exclusively in flexion as an embedded beam (cantilever) at the level of, or immediately adjacent to, the journal axis. Furthermore, when the band is formed integrally with the cuff, it is necessarily formed of the same material. Thus, the band has the same mechanical characteristics as those of the cuff, including its elastic characteristics. Where the band is applied separately, its attachment to the shell base and the transmission of the forces between it and the cuff complicates the manufacture and assembly of the boot.